Electrical cut-out operated by fluid pressure



.W. H. WELCH.

ELECTRICAL CUT-OUT OPERATED BY FLUID PRESSURE.

APPLICATION FILED MAR-1,1920.

Patented Sept. 5, 1922.

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Patented Sept. 5, 1922. V 1

UNITED STATES PATENT OFFICE.-

WALTER HENRY WELCH, OF BRISTOL, ENGLAND. ASSIGNOR TO HARVEY FROST & v

COMPANY, LIMITED, 01 LONDON, ENGLAND.

ELECTRICAL cur-our OPERATED liar FLUID PRESSURE.

Application filed March 1, 1510520; Serial No. 362,176.

To all whom it may concern:

Be it known that I, Var/ran 'HENRY 7 W nLcH,a subjectofjt-he King ofEngland, re-

siding at Bristfohin England, have invented certain new and usefulImprovements in 'Electrical Cut-Outs Operated by Flujd desired that thetemperature shall be regulated automatically by repetitive cutting offof the current whenever a predetermined pressure is reached in thegenerator.

According to this invention, a fluid pressure operated electricalcut-out having a bow spring to control the pressure-member by thrustfrom the central part of the bow spring, is characterized by the bowspring being thrust towards the pressureoperated member by screws one ateach end,

which screws are separately adjustable for the purpose hereinafterdescribed.

One of the screws may be provided with an index-arm 'which co-operateswith a scale, for example works in or beneath a slot in a wall of thecasing wherein the apparatus may be enclosed, such slot having a scaleat the side.

The invention consists in the construction arrangementand combination ofparts described hereinafter and pointed out in the claim. i

In the accompanying drawings, which illustrate one method of carryingout this invention as applied to a portable vulcan- 1zer:-

Figurel is a plan of the cut-out, part being shown broken away;

Figure 2 isa vertical section through'the same taken on the line 2-2 inFigure 1,"

and

Figure 3 is a side elevation form of a detail.

The same letters indicate the same parts throughout the drawings.

Referring to Figures 1v and 2, a plate A represents one wall of apressure-chamor a modified arm D whose end G in one wall G her which, ina vulcanizeris the steam-gencrating chamber. In this wall is an openin Awhich is covered by a diaphragm, Thls diaphragm may be merely flexibleor it maybe of resilient material, and is clamped in place by acoverplate C.

The cover-plate is hollowed at C on the side which is towards thediaphragm to allow free movement of the latter, but is preferably not sodeeply hollowed as to prevent the diaphragmfrom bearingag'ainst it whenthrust in to the limit of its movement; the plate 'C thus serves as asupportv for the diaphragm.

Above the cover-plate is a bow spring D,

the centre of which bears upon a thrustpiece B which extends through ahole C" 1n the cover-plate C and presses against the diaphragm B. Thebow spring is held in place by screws D and D one at each end, whichextend through the spring and are carried by the plateA. These screwsare adjustable in the plate so that by screwing them further in, thetension ofthe spring,

on the diaphragm may be increased, or by drawing them out, it may bedecreased, and

it will be observed that the screws can be separately adjusted.

A contact-arm E of resilient metal extends transversely across the bowspring D, being carried by a block F on the coverplate, and athrust-piece D onthe top face of the bow-spring bears against theunderside of this contact-arm at a point near its root. This arm has aconnection F? for one wire of the electrical circuitand its free endmakes contact with another contactpiece indicated at E, which is alsocarried by the cover-plate C but is insulated therefrom and providesanother connecting point E for the electrical circuit of theheatingelement.

The'screw D has a laterally-projecting projects through a slot of thecasing within which the whole apparatus may be enclosed. On this wallalong by the side of the slot is a scale G? marked in lbs. per squareinch.

The operation of this apparatus is as follows As the pressure in thegenerating-chamber rises the thrust against the diaphragm B increasesuntil the sprin D is thrust back sufficiently to cause the t rust-pieceD carried thereby to lift the contact-arm E and thus separate its freeend from the contactpiece E.

The circuit through the heating-element of the vulcanizer, or whateverother circuit the cut-out may be used for, is thus broken and thegeneration of steam ceases. As the apparatus cools down, the contact-armwill again automatically come into operation and so the apparatus may bekept automatically at any desired temperature ,forvas long a period asis required.

The screw D is used' for applying pressure to the diaphragm whenassemblingthe apparatus, so that each cut-out may be sent out to operateat a given pressure with the screw D left in such position that the armD is in the middle of the slot G.. The user can then move the arm in onedirection or the other to decrease or increase the pressure as he maydesire, and the scale will indicate how much he increases or decreasesthe ori inal setting of the apparatus.

It wi 1 be seen that this cut=out is simple to make and easilyadjustable, and moreover by employing a bow spring instead of the spiralspring usually used in such cut-outs, a flat form of apparatus isobtained which enables the cut-out to be stowed in a small compass, andmuch greater accuracy of adjustment-is found to be obtainable by use ofthe bow spring instead of a spiral spring.

If desired, the contact-arm E may made of two metals, for example steeland brass, as shown at E E, Figure 3,-secured face-to-face, the brassstrip being placed to wards the bow spring so. that should the apparatusfor any reason become overheated, the heat will be conducted by themetal parts to the said arm and cause it to bend outwards owing to thegreater ex pansion of the brass strip E relatively to the steel strip EThis bi-metallic contact arm thus constitutes an additional safetydevice. I

What I claim as m to secure by Letters atent is In a fluidpressure-operated electrical cut out, the combination with a pressuremember subjected to fluid pressure, and an electrical contact devicecomprising a movable contact member for controlling an electric circuit,of a bow spring having its central part operatively connected with saidcontact member, a screw positioning one end of the bow spring andarranged to thrust the central part thereof against said pressuremember, a plate provided with. a slot, a second. screw positioning theother end of the bow spring and arranged to thrust the central partthereof against said pressure member,'

and an index arm that is rigidly attached to the said second screw, andextends into said slot, substantially as described.

In testimony whereof I afiix my signature.

WALTER HENRY wELcH.

invention and desire v

